Improved Apparatus for Cleaning Synthetic Grass

ABSTRACT

An apparatus for cleaning synthetic grass comprising a manifold and an elongate plenum head disposed within the manifold and having a compressed air inlet and a plurality of air outlets spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of coarse and fine particulate material and to entrain the dislodged particulate material, said manifold including at least one vacuum outlet located in rearwardly of the manifold associated with a vacuum system for exit of the fine particulate material, and an open lower region of the manifold.

TECHNICAL FIELD

The present invention relates to an apparatus for cleaning synthetic grass.

BACKGROUND ART

Synthetic grass surfaces typically comprise a synthetic surface from which extends tufts of simulated grass fibres of a plastic material. A variety of mediums including but not limited to sand and rubber combination, sand or rubber and water, is laid on the surface filling the spaces between the tufts so that the tufts remain substantially erect and produce a flat surface which provides a surface suitable for use as a recreational surface. Typically, the base of the artificial turf that supports the tufts and infill is the technical layer. This typically consists of the backing layer which holds the tufts together, then the shock absorber layer, then a compacter layer consisting of crushed rock then a drainage layer. This however may vary between the systems but traditionally consists of these core components. Compaction also affects the drainage of the artificial playing field leading to the shock pad degrading at an accelerated rate. Typical artificial playing fields can consist of, football, field hockey, baseball, softball, La Crosse, Soccer, Rugby, Tennis, Physical education Etc.

Typically synthetic grass is very durable. Typical grime, mould and mildew collects on the infill causing it to agglomerate, as well as penetrate down through the shock pad (this is typically the first layer of the technical layer) limits the ability of the infill to stabilise the tufts leading to premature degradation and a reduction in performance This reduction in performance is a result of hardening of the shock pad and may cause rotting of this layer. This can also cause the tufts to collapse, making the playing surface dangerous. Bacteria and algae also cases issued with the playing surface as it can become slippery under humid conditions. The contaminants can cause hard sports on the playing surface creating potential for skin abrasions but can cause the abrasions to become septic depending on the nature of the contaminants. The compaction which leads to the fibres bending over can cause erratic ball characteristics affecting the game being played.

Because the synthetic grass is porous, whenever rain falls, dust and contaminants rise to the surface of the synthetic grass fibres causing the fibres to collapse, leading to degradation in turf quality and consequential problems for the sporting activity for which the synthetic grass is being used.

Rotary brushing is generally ineffective in breaking up aggregated particulate matter and can in fact damage the fibres of the synthetic grass surface. Rotary brushing does not remove dust and other contaminants, it merely redistributes these contaminants which are believed to be the main cause of aggregation of sand particles, the consequential compaction of fibres and the growth of algae and moss.

Another solution currently used is to use detergent and chemicals to try and clean playing fields. However, to try to clean an entire playing surface in conjunction with the brushes is time consuming and the results are poor. As well as this the detergents and chemicals can strip the UV protection off the grass fibres allowing them to become brittle. After a clean using the detergents or chemicals the field must be thoroughly rinsed to ensure all traces of the chemicals are removed. Accordingly, there is a need for an apparatus which can effectively remove particulate material as well as organic material such as mould and mildew from deep within the synthetic grass.

In the past, cleaning a synthetic grass surface has been performed with high-pressure water. Cleaning in this manner is a very untidy process and time consuming, and usually requires the replacement of much of the infill and also a considerable amount of re-levelling. Re-levelling is difficult with wet infill and is a particularly laborious, time-consuming process. As well as this, the method of delivering the high pressure water, can damage the playing surface due to a heavy vehicle being on the playing field. This process is environmentally unfriendly due to the amount of water required to carry out an adequate cleaning process. This defeats the purpose of having the artificial turf.

Machines for cleaning synthetic grass surfaces are also known. The machines generally pass over the surface and have a front head attachment which blows high-pressure air against the ground surface to be cleaned. The head attachment has a shroud in which a plenum chamber is located and through which plenum chamber the high-pressure air passes against the ground surface. The pressurized air was dispersed onto the synthetic grass surface using a perforated drum which expelled air at a fixed angle onto the synthetic grass surface as the machine passed over the surface. The high-pressure air breaks up any dirt, debris, moss, caked sand, dust, and the like, and some separation of dust and sand is achieved by virtue of a powerful vacuum arrangement in the head attachment. The cleaned sand passes through the baffles and back onto the playing surface, while the dust, dirt, and the like passes through an outlet and into collection bags. Because the head attachment is not very efficient in separating dust from sand, much sand also passes into the collection bags and therefore the collection bags are arranged upwardly with a lower inlet such that the heavier sand passes back through the inlet and into a sand collecting chamber. An example of this apparatus is described in Australian Patent No. 647607.

While this apparatus was satisfactory for some users, it was found that too much sand was being removed from the playing surface. The upward vertical collection bags were also quite dangerous as they were fully exposed and tended to flap in the wind. The apparatus was also not suitable for any cleaning other than separating dust from sand, and thus the apparatus was more or less limited to tennis courts.

An improved model of this apparatus was developed in which a baffle was located within a shroud of the head attachment and above the plenum chamber, the baffle having a first leading portion joined to an inner wall of a leading portion of the shroud, and also having a trailing portion spaced inwardly from the trailing portion of the shroud. Accordingly, the baffle formed a tortuous pathway for dust thrown up by the compressed air to pass through the outlet. This arrangement considerably improved the separation of dust and sand meaning that a minimum amount of sand passed through the outlet into the collection bags.

Again, while the cleaning achieved this apparatus performed was satisfactory, it was still found that too much sand was being removed from the playing surface. The machine also tended to flatten the synthetic grass fibres or force them to adopt a prone condition. This reduces the effectiveness of the cleaning performed and also the quality of the synthetic grass surface after cleaning.

A further apparatus was then developed for cleaning a synthetic grass surface having a plenum head and a manifold, the plenum head disposed within the manifold and having a compressed air inlet and at least one air outlet through which air can be expelled against the synthetic grass surface for dislodgement of coarse and fine particulate material and to entrain the dislodged particulate material into the manifold which extends above said plenum head, said manifold including an outlet located in an upper region of the manifold for expelling the fine particulate material, and an outlet in a lower region of the manifold for distributing the coarse particulate material back to the synthetic grass surface, wherein the plenum head is mounted for rotation within the manifold about a substantially vertical axis.

However, it has been found that the rotating head can leave rills in the cleaned surface.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

SUMMARY OF INVENTION

The present invention is directed to an apparatus for cleaning synthetic grass, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

With the foregoing in view, the present invention in one form, resides broadly in an apparatus for cleaning synthetic grass comprising a manifold and an elongate plenum head disposed within the manifold and having a compressed air inlet and a plurality of air outlets spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of coarse and fine particulate material and to entrain the dislodged particulate material, said manifold including at least one vacuum outlet located in a rear area of the manifold for exit of the fine particulate material, and an open lower region of the manifold for distributing the coarse particulate material back to the synthetic grass surface.

In an alternative aspect, the present invention resides in an apparatus for cleaning synthetic grass comprising a manifold and an elongate plenum head disposed within the manifold and having a compressed air inlet and a plurality of air outlets spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of particulate detritus, said manifold including a vacuum outlet located rearwardly of the manifold to exit of the particulate detritus, and an open lower region of the manifold, the manifold having at least one inlet therein to allow additional air or water to be provided into the manifold.

The additional air or water to be provided into the manifold will normally depend upon the configuration of the device and whether the device is adapted to clean water infill synthetic grass or sand infill or no infill synthetic grass.

The apparatus is suitably arranged on a framework which permits easy manipulation over the surface to be cleaned. An arrangement for removing the separated lightweight matter (debris) and collecting it may also be included on such a framework. Most preferably, the framework is wheeled so that the device may be pushed or driven over the surface to be cleaned.

The plenum head is preferably an elongate member, most suitably oriented substantially horizontally. The length of the plenum head is such that it preferably extends from one side of the manifold to the other, that is, when the plenum head is oriented widthwise across the manifold, it is arranged such that it extends at approximately right angles to the direction in which the device is adapted to move or be propelled over the ground surface. The plenum head may be mounted centrally in relation to the manifold by any suitable means. The compressed air supply may be fed to the plenum head using any configuration.

The plenum head has at least one compressed air inlet mounted approximately centrally along its length, and at least one outlet of relatively reduced size which creates an increase in the velocity of the air passing therethrough. Alternatively, the plenum head may have an inlet located at or through one end of the plenum head which is preferably communicable with an air supply located externally of the manifold.

It is particularly preferred that the plenum head is elongate and tubular, of substantially circular cross-section. Preferably, the at least one outlet directs the air at an angle downwardly beneath the apparatus, against the surface to be cleaned and particularly the particulate matter to be dislodged from the synthetic grass surface, and entrains the dislodged material in the air flow.

Each outlet may be one or more narrow slits, nozzles or orifices. There may suitably be a plurality of outlets preferably extending substantially linearly along an arm of the plenum head or, most preferably, a multiplicity of aligned pin holes or nozzles. Preferably, the nozzles or the like are disposed and directed slightly forwardly of the plenum head. The nozzles may be angled at any angle relative to the surface to be cleaned but there are likely to be angles which will be optimal under different circumstances.

Of course, other configurations of the outlets are anticipated and the particular configuration may be chosen according to the condition of the synthetic surface or the degree of cleaning required. In one form, the plenum head may be in the form of an arm extending across the width of the manifold and mounted approximately centrally. The apparatus may be provided with a number of interchangeable plenum arm members, each having a different configuration of outlets, each arm member and configuration designed to provide different aspects of cleaning to the surface.

Suitably, the internal bore of each outlet is configured so that a venturi effect is produced by the air passing therethrough. The angle at which the outlet(s) is arranged is such as to provide maximum leverage on the particulate matter to be dislodged, whilst simultaneously directing the dislodged matter towards the vacuum outlet of the manifold. A suitable angle may be between 30° and 75°, most preferably about 60° with respect to the synthetic surface. The number of outlets in the plenum head will ideally be maximized so that a large number of individual jets of fast moving air can be directed against the surface, thereby optimising the dislodgment forces on the particulate material. As the plenum head having the outlets extending along the length of the head is moved laterally over the surface to be cleaned, the cleaning provided may be more effective due to a variation in the angle of the air striking the surface.

The compressed air outlets may be positioned at a particular height above the surface in order to provide the cleaning effect. This height (or separation distance) may typically be approximately 5 mm but the height may be variable by adjusting the separation distance between the plenum arm member and the surface. Height adjustment means may be provided for this purpose.

The manifold preferably has a forward portion which is at least partially arcuate. The manifold also has a top wall extending rearwardly of the forward portion, a rear wall and a pair of sidewalls. This configuration has been found to be useful for a rotating plenum head.

For a fixed plenum head, the manifold is typically rectangular with a planar forward wall. This will also allow cleaning into corners of a field or into areas with restricted access. By “fixed”, the inventor intends to convey that the plenum head does not rotate about a substantially vertical axis, that is it maintains its orientation. A “fixed” head may still rotate about a horizontal axis.

The manifold will typically be manufactured of a light metal but it is anticipated that in some instances, a heavy duty (to resist the abrasive effect and/or withstand higher pressures) plastic/composite may be used. It may also be preferred that the manifold be manufactured of a composite material in order to provide desired properties, such as abrasion and corrosion resistance, and also to reduce the weight of the manifold to reduce fatigue on the apparatus, particularly the mounting portions.

In the preferred embodiments, a rear portion of the manifold is rectangular when viewed in plan. This preferably allows the vacuum outlet to extend across the width of the rear of the manifold. The manifold is preferably provided with a substantially vertical rear wall which is also preferably planar. It is particularly preferred that the vacuum head is located in the lower portion of the substantially vertical rear wall.

The vacuum head is preferably attached via an appropriate conduit to at least one vacuum pump, which are provided as part of the apparatus. It has been found that the particularly preferred vacuum pumps each discharge approximately 120 ft.³ per minute as exhaust in order to create the vacuum.

The manifold also has an open bottom for distributing the coarse particulate material back to the synthetic grass surface.

The system preferably operates to provide fluid, generally compressed air to the plenum head to dislodge detritus from the surface or from within the synthetic grass mat in order to allow the vacuum system to remove the detritus. The system may include one or more recycled fluid streams of air or a liquid such as water.

In some potential configurations, at least one and normally at least a pair of ducts are mounted in a forward area of the manifold and directed toward the vacuum outlet in the rear of the manifold. Preferably, each duct is fed by the discharge air from an exhaust side of a vacuum pump connected to the vacuum outlet of the manifold, but could be fed by an independent air source.

The preferred ducts provide a flow of air directed rearwardly in the manifold which assists with entrainment of the lighter material which is dislodged from the surface to be cleaned and moving the lighter material into the vacuum head.

Preferably, two ducts are provided, each duct is preferably associated with one of the preferred pair of vacuum pumps. Preferably, the exhaust from the vacuum pumps is directed into the ducts.

Each of the ducts is preferably at least partially conical or at least convergent from the inlet of the duct to the outlet of the duct in order to increase the velocity of the air at the duct exit. Normally, the ducts will extend through a sidewall of the manifold and will normally be located in an upper portion of the manifold. Preferably, the ducts are located above the plane of the plenum head so as not to interfere with the pressure of the air from the air outlets.

Each duct will preferably have a shaped outlet in order to disperse the air within the manifold. Preferably, the dispersion is in a substantially horizontal plane so as to better direct airflow towards the vacuum head. The location of the ducts within the manifold will also preferably minimise debris sticking to the underside of the manifold through the creation of more chaotic air patterns within the manifold. This may also help to reduce rills in the cleaned surface.

In another preferred configuration, and particularly when used to clean synthetic surfaces with water infill, a water recycle may be used. In other words, one or more water return inlets may be provided in the housing of the cleaning head in order to allow water collected by the vacuum system to be returned to the head once the detritus has been separated from the water.

The plenum head and/or the nozzles may have a protective coating or similar applied thereto to reduce the abrasion, attrition or scarifying effect from sand or other detritus which may be forcibly ejected from the surface being cleaned. A particularly preferred coating may have a resilient or rubber-like finish.

As previously mentioned, the apparatus is preferably supported on a wheeled framework. Such a framework is preferably of tubular construction with thin gauge sheet metal walls for minimising the weight of the entire apparatus. If the apparatus is designed to be pushed by a user, a push/pull handle bar is suitably provided at waist-height for easy manipulation, and means enabling the manifold to be lowered close to the ground surface or for raising it when not in use are also included. Such means can comprise a set of pivotal linkages operated by a lever adjacent the push/pull handle.

According to a particularly preferred embodiment, the apparatus may be supported on a self-propelled machine such as a golf buggy or similar machine. The apparatus may be associated with means enabling the height of the manifold, and therefore the plenum head, to be raised and lowered relative to the ground surface to obtain the optimum height for cleaning the synthetic grass surface. The height adjustment means may include a set of pivotal linkages attached to the manifold operated by a lever for example.

An arrangement may be provided for separating the fine particulate material and removing it. This arrangement may be as simple as a filter bag similar in operation to a vacuum filter bag. More complex or advanced systems may be provided depending upon requirements. In particular, a self-cleaning filtering configuration will be preferred.

When a complex arrangement is provided for removing the separated fine particulate matter and collecting it, this will suitably comprise a cyclone and chamber used in combination with a filtering system. The cyclone is conveniently connected directly by way of a flexible duct to the port of the manifold. An inlet is provided in the sidewall of the cyclone at an intermediate position, and internal plates direct the entrained fine particulate matter around the inner wall towards the bottom of the cyclone to a collection chamber directly beneath it. A filtering system may be provided about an exhaust air outlet, or outlets, which is preferably located in the top of the cyclone. The filtering system may comprise one or more bags of filtering material supported from a framework which extends above the outlet(s). The filtering arrangement is designed to prevent any fine particulate matter blowing into the atmosphere while permitting the exhaust air to be expelled therethrough.

Compressed air used to charge the plenum head can be supplied from a compressor which is either carried by the support framework for the apparatus or is supplied by a separate remote compressor.

Compressed air used to in the plenum head can be supplied from a compressor which is either carried by the support framework for the apparatus or is supplied by a separate remote compressor.

It is particularly preferred that a multistage compressor or fan is used. A multistage unit normally contains a series of impellers on a single shaft rotating within a casing. The intake air is progressively compressed in the different stages. A particularly preferred multistage compressor which may find use in the present invention is a four stage compressor with impeller diameters of approximately 300 mm, 200 mm, 100 mm and 50 mm in each of the stages leading to an approximately 15 mm compressed air outlet. This unit is typically small enough to obviate the requirement for any cooling of the compressor beyond basic air cooling.

According to a particularly preferred embodiment, the compressed air may be supplied to the surface to be cleaned at a relatively low volume, (approximately 100 cubic feet per minute) but at a relatively high pressure (approximately 250 pounds per square inch). There may be an adjustment means provided to adjust the flow rate and/or pressure at which the compressed air is provided. For example, particularly high use areas of the surface, such as those about the service line on a tennis court, may require a more intensive cleaning than other, less well used areas. In this situation, a higher pressure flow at a lower flow rate may be used to clean the high use areas due to greater compaction of the surface at those areas while a lower pressure flow at a higher flow rate may be used at the lower use areas.

It may also be a compressed air feed into the vacuum exit port from the manifold in order to create a Venturi effect which may assist with removal of heavier particles.

According to the present invention, the plenum head may rotate about a substantially vertical axis or alternatively, may be fixed substantially perpendicularly to the direction of travel. According to a particularly preferred embodiment, the apparatus used to clean wet synthetic grass surfaces will utilise a rotating plenum head and the apparatus used to clean dry synthetic grass surfaces will utilise a fixed plenum head. Where provided in a rotating embodiment, it is preferred that the air outlets on the rotating plenum head are provided in groups one at either end of the plenum head.

There may also be a mechanism by which a rotating plenum head can be fixed to allow one machine to be used in both the wet or dry configurations.

According to a preferred embodiment of the present invention, the assembly may include an ultraviolet sterilisation assembly. This assembly may be provided within the manifold, preferably within a recessed area in an upper portion of the manifold but directed downwardly to sterilise the surface directly. Alternatively or in addition, an ultraviolet sterilisation assembly may be provided to sterilise any water which may be left on the playing surface.

Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

FIG. 1 is a view from below the manifold of an apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a side elevation view of the arrangement illustrated in FIG. 1.

FIG. 3 is a sectional side elevation view of the arrangement illustrated in FIG. 1 along line A-A.

FIG. 4 is a sectional side elevation view of the configuration illustrated in FIG. 1 along line A-A showing the compressed air supply conduit.

FIG. 5 is a view from below of the manifold of an apparatus according to an alternative preferred embodiment of the present invention.

FIG. 6 is a sectional side elevation view of the configuration illustrated in FIG. 5 along line B-B.

FIG. 7 is a sectional side elevation view of the configuration illustrated in FIG. 5 along line B-B showing the compressed air supply conduit.

FIG. 8 is a view from below the manifold of the configuration illustrated in FIG. 5.

FIG. 9 is a schematic sectional view of a preferred air compressor or stage compression fan according to a preferred embodiment of the present invention.

FIG. 10 is a front elevation view of a plenum head according to a preferred embodiment of the present invention.

FIG. 11 is an end view of the configuration illustrated in FIG. 10.

FIG. 12 is a detailed view of the configuration illustrated in FIG. 11.

FIG. 13 is an isometric view from a first side of a preferred embodiment of the present invention adapted to clean synthetic surfaces with water infill.

FIG. 14 is an isometric view from a second side of the embodiment illustrated in FIG. 13.

FIG. 15 is a side view of the embodiment illustrated in FIG. 13.

FIG. 16 is a top view of the embodiment illustrated in FIG. 13.

FIG. 17 is an isometric view from a first side of a preferred embodiment of the present invention adapted to clean synthetic surfaces with sand infill.

FIG. 18 is an isometric view from a second side of the embodiment illustrated in FIG. 17.

FIG. 19 is a side view of the embodiment illustrated in FIG. 17.

FIG. 20 is a top view of the embodiment illustrated in FIG. 17.

FIG. 21 is a process flow diagram of the embodiment illustrated in FIG. 17.

FIG. 22 is an isometric view of a preferred embodiment of the present invention adapted to clean synthetic surfaces with water infill similar to that illustrated in FIG. 13 but in a more complete, assembled form.

FIG. 23 is a process flow diagram of the embodiment illustrated in FIG. 22.

DESCRIPTION OF EMBODIMENTS

According to a particularly preferred embodiment of the present invention, an apparatus for cleaning synthetic grass is provided.

One preferred form of apparatus for cleaning synthetic grass is illustrated in the accompanying Figures and includes a manifold 10 and a rotating elongate plenum head 11 disposed within the manifold 10 and having a compressed air inlet 12 and a plurality of air outlets 13 spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of coarse and fine particulate material and to entrain the dislodged particulate material. The manifold 10 also includes a vacuum outlet 14 located in a rear area of the manifold 10 for exit of the fine particulate material, and an open lower region of the manifold 10 for distributing the coarse particulate material back to the synthetic grass surface.

The apparatus is suitably arranged on a framework which permits easy manipulation over the surface to be cleaned. An arrangement for removing the separated lightweight matter (debris) and collecting it may also be included on such a framework. Most preferably, the framework is wheeled so that the device may be pushed or driven over the surface to be cleaned.

The plenum head 11 of the illustrated embodiment an elongate member oriented substantially horizontally. As illustrated in FIG. 1 as an example, the length of the plenum head 11 is such that it extends from one side of the manifold 10 to the other, that is, when the plenum head 11 is oriented widthwise across the manifold 10, it is arranged such that it extends at approximately right angles to the direction in which the device is adapted to move or be propelled over the ground surface.

The plenum head is mounted centrally in relation to the manifold 10 from a flange arrangement 16 which also attaches the compressed air supply conduit 15. The compressed air supply conduit 15 is fixed and the plenum head 11 is mounted at a lower end of a rotating supply conduit 17.

The plenum head 11 has a compressed air inlet 12 mounted approximately centrally along its length, and a number of outlets 13 of relatively reduced size which creates an increase in the velocity of the air passing therethrough.

A preferred form of plenum head is elongate and tubular of substantially circular cross-section. This is the case in both the fixed and rotating embodiments as is the orientation of the outlets. Although the particular embodiment of the plenum head illustrated in FIGS. 10 to 12 is the fixed embodiment (having the outlets spaced over its length rather than in groupings toward each end as in the rotating embodiment illustrated in the remaining Figures) the outlets direct the air at an angle downwardly beneath the apparatus against the surface to be cleaned and particularly the particulate matter to be dislodged from the synthetic grass surface and entrains the dislodged material in the air flow.

A preferred embodiment of the plenum head used according to the fixed embodiment of the present invention is illustrated in FIGS. 10 to 12. The plenum head 11 extends substantially horizontally across the width of the manifold and is attached to manifold using a stud 51 at either end. Compressed air flows into the plenum head 11 through a T-connection 52 approximately halfway along the width of the head 11. The stud 51 is welded 91 into each end of the manifold pipe 50.

As best illustrated in FIG. 12, spaced across the width of the plenum head 11 are a number of nozzles 54 in order to direct the air at the surface to be cleaned. The nozzles are oriented at approximately 45° and can be directed either forwardly or rearwardly.

Suitably, the internal bore of each nozzle is configured so that a venturi effect is produced by the air passing therethrough. The angle at which the outlet(s) is arranged is such as to provide maximum leverage on the particulate matter to be dislodged, whilst simultaneously directing the dislodged matter towards the vacuum outlet of the manifold. A suitable angle may be between 30° and 75°, most preferably about 45° with respect to the synthetic surface for the fixed head and approximately 60° for the rotating head. The number of outlets in the plenum head will ideally be maximized so that a large number of individual jets of fast moving air can be directed against the surface, thereby optimising the dislodgment forces on the particulate material. This is particularly important when the particulate matter has formed a hard crusty surface as is quite common in tennis court surfaces. As the plenum head 11 having the outlets 13 extending along the length of the head 11 is moved laterally over the surface to be cleaned, the cleaning provided may be more effective due to a variation in the angle of the air striking the surface.

The compressed air outlets 13 may be positioned at a particular height above the surface in order to provide the cleaning effect. This height may typically be approximately 5 mm but the height may be variable by adjusting the separation distance between the plenum head 11 and the surface. Height adjustment means may be provided for this purpose andit may be achieved by manipulating the flange arrangement.

The apparatus may be provided with a number of interchangeable plenum arm members, each having a different configuration of outlets, each arm member and configuration designed to provide different aspects of cleaning to the surface.

The manifold 10 of the rotating plenum head embodiment illustrated in FIGS. 1 to 8 has a forward portion which is at least partially arcuate. The manifold also has a top wall extending rearwardly of the arcuate forward portion, a rear wall and a pair of sidewalls. This configuration has been found to be optimal for a rotating plenum head.

For a fixed plenum head, the manifold is typically rectangular with a planar forward wall. This will also allow cleaning into corners of a field or into areas with restricted access.

In the preferred embodiments, a rear portion of the manifold 10 is rectangular when view in plan. This allows the vacuum outlet 14 to extend across the width of the rear of the manifold 10 as illustrated in FIGS. 1, 5 and 8. The manifold is preferably provided with a substantially vertical rear wall 18 which is also preferably planar. It is particularly preferred that the vacuum outlet is located in the lower portion of the substantially vertical rear wall.

The vacuum outlet or head 14 is preferably attached via appropriate conduit 19 to at least one vacuum pump, and normally a pair of vacuum pumps which are provided as part of the apparatus. It has been found that the preferred vacuum pumps each discharge approximately 120 ft.³ per minute at the exhaust in order to create the vacuum.

The manifold also has an open bottom for distributing the coarse particulate material back to the synthetic grass surface although this may have a mesh or similar in order to prevent large debris such as sticks or the like obstructing the plenum head 11.

In the preferred embodiment illustrated in FIGS. 5 to 8, a pair of ducts 20 are mounted in a forward area of the manifold 10 and directed toward the vacuum outlet 14 in the rear of the manifold 10. Preferably, each duct 20 is fed by the discharge air from an exhaust side of a vacuum pump connected to the vacuum outlet 14 of the manifold.

The preferred ducts 20 provide a flow of air directed rearwardly in the manifold 10 which assists with entrainment of the lighter material which is dislodged from the surface to be cleaned and moving the lighter material into the vacuum outlet 14.

Preferably, two ducts are provided, each duct preferably associated with one of the preferred pair of vacuum pumps with the exhaust from one of the vacuum pumps directed into one of the ducts.

As illustrated, each of the ducts 20 is at least partially conical or at least convergent from the inlet of the duct to the outlet of the duct in order to increase the velocity of the air at the duct exit. Normally, the ducts 20 extend through sidewall of the manifold 10 and are be located in an upper portion of the manifold.

Each duct 20 preferably has a shaped outlet in order to disperse the air within the manifold. Preferably, the dispersion is in a substantially horizontal plane so as to better direct airflow towards the vacuum head 14. The location of the ducts within the manifold will also preferably minimise debris sticking to the underside of the manifold 10 through the creation of more chaotic air patterns within the manifold surface.

As previously mentioned, the apparatus is preferably supported on a wheeled framework. According to a particularly preferred embodiment, the apparatus may be supported on a self-propelled machine. The apparatus may be associated with means enabling the height of the manifold, and therefore the plenum head, to be raised and lowered relative to the ground surface to obtain the optimum height for cleaning the synthetic grass surface.

An arrangement may be provided for separating the fine particulate material and removing it. This arrangement may be as simple as a filter bag similar in operation to a vacuum filter bag. More complex or advanced systems may be provided depending upon requirements. In particular, a self-cleaning filtering configuration will be preferred.

When a complex arrangement is provided for removing the separated fine particulate matter and collecting it, this will suitably comprise a cyclone and chamber in combination with a filtering system. The cyclone is conveniently connected directly by way of a flexible duct to the port of the manifold. One form of cyclone comprises a cylinder with a conical head piece which is oriented in a vertical location on the wheeled framework between the manifold and the push/pull handle. An inlet is provided in the sidewall of the cyclone at an intermediate position, and internal plates direct the entrained fine particulate matter around the inner wall towards the bottom of the cyclone to a collection chamber directly beneath it. A filtering system may be provided about an exhaust air outlet, or outlets, which is preferably located in the top of the cyclone. The filtering system may comprise one or more bags of filtering material supported from a framework which extends above the outlet(s). The filtering arrangement is designed to prevent any fine particulate matter blowing into the atmosphere while permitting the exhaust air to be expelled therethrough.

Compressed air used to charge the plenum head can be supplied from a compressor which is either carried by the support framework for the apparatus or is supplied by a separate remote compressor.

It is particularly preferred that a multistage compressor or fan is used. A multistage compressor normally contains a series of impellers 22 on a single shaft rotating within a casing. The intake air is progressively compressed in the different stages. A particularly preferred multistage compressor which may find use in the present invention is a four stage compressor with impeller diameters of approximately 300 mm, 200 mm, 100 mm and 50 mm in each of the stages leading to an approximately 15 mm compressed air outlet 21 as illustrated schematically in FIG. 9. This unit is typically small enough to obviate the requirement for any cooling of the compressor beyond basic air cooling.

According to a particularly preferred embodiment, the compressed air may be supplied to the surface to be cleaned at a relatively low volume, (approximately 100 cubic feet per minute) but at a relatively high pressure (approximately 250 pounds per square inch). There may be an adjustment means provided to adjust the flow rate and/or pressure at which the compressed air is provided. For example, particularly high use areas of the surface, such as those about the service line on a tennis court, may require a more intensive cleaning than other, less well used areas. In this situation, a higher pressure flow at a lower flow rate may be used to clean the high use areas due to greater compaction of the surface at those areas while a lower pressure flow at a higher flow rate may be used at the lower use areas.

According to the present invention, the plenum head may rotate about a substantially vertical axis or alternatively, may be fixed substantially perpendicularly to the direction of travel. According to a particularly preferred embodiment, the apparatus used to clean wet synthetic grass surfaces will utilise a rotating plenum head and the apparatus used to clean dry synthetic grass surfaces will utilise a fixed plenum head. Where provided in a rotating embodiment, it is preferred that the air outlets on the rotating plenum head are provided in groups one at either end of the plenum head.

According to a preferred embodiment of the present invention, the assembly may include an ultraviolet sterilisation assembly. This assembly may be provided within the manifold, preferably within a recessed area in an upper portion of the manifold but directed downwardly to sterilise the surface directly. Alternatively or in addition, an ultraviolet sterilisation assembly may be provided to sterilise any water which may be left on the playing surface.

An alternative embodiment of a device adapted to clean synthetic surfaces with water infill (a “wet” system) is illustrated in FIGS. 13 to 16 and 22 to 23.

As illustrated in FIGS. 13 to 16, the device is based around a chassis which supports a cabin 131 having controls to control the movement of, what is in effect, a self-propelled vehicle 130, as well as controls to control the operation of the equipment mounted to the chassis, a rear cabinet 132 containing the process equipment and a cleaning head 133 provided in front of the cabin 131. As illustrated in the Figures, the rear cabinet 132 has a pair of side doors 134 which can be opened and closed in order to access the process equipment within the rear cabinet 132. The doors 134 are normally closed during operation but can be opened as required.

The vehicle 130 is self-propelled operating on four wheels. The vehicle is electrically driven. The vehicle 130 is driven by an operator who is also responsible for the operation of the process equipment associated with the cleaning head 133.

As mentioned above, the rear cabinet 132 of the vehicle illustrated in FIG. 13 includes a diesel engine 135 in order to power the process equipment. The diesel engine 135 is typically controlled via a hand throttle 136 which is located in the cabin of the vehicle. The hand throttle 136 typically controls the operating speed of the diesel engine 135.

The rear cabinet 132 also includes a compressor 137 in order to provide compressed air to the plenum chamber in the cleaning head 133 as well as to provide air to the pneumatic ram 138 for positioning the cleaning head 133. The preferred compressor 137 is a screw compressor which may be a multistage screw compressor. In this way, the compressor 137 can provide compressed air at sufficient volume and pressure to the plenum chamber in the cleaning head 133 and also provide air to the pneumatic ram 138 at a lower pressure in order that the cleaning head 133 exert only slight or neutral pressure on the surface which is being cleaned. As illustrated in FIG. 23, the compressor 138 is preferably driven via a belt associated with the diesel engine 135.

The rear cabinet 132 also preferably includes a centrifugal fan 139 in order to create the required vacuum. The centrifugal fan 139 is also typically driven via a belt by the diesel engine 135. The volumetric flow rate of centrifugal fan 139 is typically much greater than that of the compressor 138 in order to create the vacuum required.

As illustrated in FIG. 23, the inlet of the centrifugal fan 139, which in the preferred embodiment is a squirrel cage fan, is linked to the outlet of a vacuum barrel 140 with the inlet of the vacuum barrel 140 linked to the outlet of a wet filter barrel 141 and the inlet of the wet filter barrel 141 linked by conduit 142 to the vacuum heads 143 provided on or adjacent to the cleaning head 133. This configuration is illustrated more clearly in FIG. 22 which also shows the split extractor conduits 152 linking the vacuum conduit 142 to the fan. A rubber skirt 153 or similar is provided at a lower portion of the cleaning head housing.

The vacuum barrel 140 of the preferred embodiment is a stainless steel barrel which is generally cylindrical in shape and approximately 1200 mm high by approximately 400 to 450 mm in diameter. The preferred embodiment measures 1150 mm high and 420 mm in diameter. The vacuum barrel 140 has a detachable lid which is removably attached using screw down toggles. Appropriate seals are also provided between the lid and the vacuum barrel in order to seal the barrel in order to create the vacuum. Preferably, a discharge or drain will be associated with a lower end of the vacuum barrel 140 although one or more valves may be provided in order to control the discharge from the vacuum barrel 140. The vacuum barrel 140 of the preferred embodiment also preferably includes a liquid reservoir 144 associated therewith and preferably, the reservoir 144 is located in a lower portion of the vacuum barrel 140 as illustrated in FIG. 23.

The wet filter barrel 141 of the preferred embodiment is also a stainless steel barrel which is generally cylindrical in shape and approximately 1200 mm high by approximately 400 to 450 mm in diameter. Again, in the preferred embodiment, the wet filter barrel 141 measures 1150 mm high and 420 mm in diameter. The wet filter barrel 141 has a detachable lid which is removably attached using screw down toggles. Appropriate seals are also provided between the lid and the wet filter barrel 141 in order to seal the wet filter barrel 141. Preferably, a discharge or drain will be associated with a lower end of the wet barrel although one or more valves as illustrated in FIG. 23 may be provided in order to control the discharge from the wet filter barrel 141. The wet filter barrel 141 of the preferred embodiment also preferably includes a liquid reservoir 144 associated therewith, and preferably, the reservoir is located in a lower portion of the wet filter barrel 141 as illustrated in FIG. 23.

The wet filter barrel 141 also functions as a filter barrel. In particular, a filter bag 145 is located inside a perforated basket 146 which is located inside the wet filter barrel 141. The filter bag 145 is typically attached to a portion of the conduit 142 or inlet extending into the wet filter barrel 141 on the barrel lid. The perforated basket 146 preferably supports the bottom on both sides of the filter bag 145 within the wet filter barrel 141 in order to prevent blowout of the filter bag 145. In the illustrated embodiment, the filter bag is a 100μ filter.

The wet filter barrel 141 typically contains water and the water level within the wet filter barrel 141 is important. The water level is typically maintained at the top of the basket 146 and slightly above the top of the filter bag 145. This allows the water to act as a plug to prevent the vacuum exerted by the fan 139 sucking air into the vacuum system and thereby into the centrifugal fan 139.

The reservoirs of both the vacuum barrel 140 and the wet filter barrel 141 preferably associated with a pump 147 in order to allow water collected in these reservoirs 144 to be conveyed to the cleaning head 133.

According to the preferred embodiment, a pair of water return inlets 148 (spray jets) are provided in the housing of the cleaning head 133 in order to provide liquid (water) into the cleaning head 133. Provision of a pair of water inlets 148 allows the water to be spread more effectively across the dimension of the cleaning head 133. A relatively small but steady flow of water is preferably provided through the pair of water inlets 148. The provision of water into the cleaning head 133 assists with the maintenance of the particulate detritus released from the surface in suspension in order to allow the vacuum to more easily collect the water with the suspended particular detritus.

According to the preferred embodiment, a first water inlet is provided forward of the rotational axis 149 of the plenum head 150 and a second water inlet is provided rearwardly of rotational axis 149 of the plenum head 150. It is preferred that both water inlets 148 are provided substantially in line with the rotational axis 149 and generally parallel with the direction of travel of the vehicle 130.

As illustrated, the cleaning head 133 itself as a rectangular housing with a rotating plenum head 150 are provided therein. The plenum head 150 rotates around a substantially vertical axis 149. The plenum head 150 is provided with a group of compressed air outlets at either end of the plenum head 150. Compressed air is supplied to the plenum head from the compressor 137 via an elongate conduit 151.

As illustrated in FIG. 13, a pair of vacuum heads 143 are preferably provided behind the plenum head 150. In FIG. 13, the vacuum heads 143 are illustrated as being separate to the cleaning head housing but in FIG. 22, the vacuum heads 143 have been incorporated into the cleaning head housing, but separated from the portion of the cleaning head housing in which the plenum head 150 is located.

Preferably, a pair of vacuum heads 143 are provided, side-by-side one another such that the vacuum effect extends across the width of the cleaning head 133 and behind the plenum head 150. The position of the vacuum heads 143 is preferably adjustable relative to the cleaning head 133 both longitudinally and in separation distance from the cleaning surface. The vacuum heads 143 are typically attached via a conduit 142 extending across the top of the vehicle and the rear cabinet 132 in particular to the wet filter barrel 141 located on the rear of the vehicle 130.

An embodiment of a device adapted to clean synthetic surfaces with sand infill (a “dry” system) is illustrated in FIGS. 17 to 21.

The device illustrated in FIGS. 17 to 21 has many similar components to that illustrated in FIGS. 13 to 16 but it is immediately clear that this device is smaller than the device illustrated in FIGS. 13 to 16.

The device is also based around a chassis which supports the cabin 171 having controls to control the movement of, what is in effect, a self-propelled vehicle, as well as controls to control the operation of the equipment mounted to the chassis, a rear cabinet 172 containing the process equipment and a cleaning head 173 provided in front of the cabin 171. As illustrated in FIGS. 17 to 21, the rear cabinet 172 has a pair of side doors 174 which can be opened and closed in order to access the process equipment within the rear cabinet 172. The doors 174 are normally closed during operation but can be opened as required.

The vehicle illustrated in FIGS. 17 to 21 is self-propelled operating on three wheels. The vehicle is electrically driven. The vehicle is driven by an operator who is also responsible for the operation of the process equipment associated with the cleaning head 173.

As mentioned above, the rear cabinet 172 of the vehicle illustrated in FIG. 17 includes a diesel engine 175 in order to power the process equipment. The diesel engine 175 is typically controlled via a hand throttle which is located in the cabin 171 of the vehicle. The hand throttle typically controls the operating speed of the diesel engine 175.

The rear cabinet 172 also includes a compressor 176 in order to provide compressed air to the plenum chamber in the cleaning head 173 as well as to provide air to the pneumatic ram 177 for positioning the cleaning head 173. The preferred compressor 176 is a screw compressor which may be a multistage screw compressor. In this way, the compressor 176 can provide compressed air at sufficient volume and pressure to the plenum chamber and also provide air to the pneumatic ram 177 at a lower pressure in order that the cleaning head 173 exerts only slight or neutral pressure on the surface which is being cleaned. The compressor 176 is preferably driven via a belt associated with the diesel engine 175 as illustrated n FIG. 21.

The rear cabinet 172 also includes a centrifugal fan 178 in order to create the required vacuum. The centrifugal fan 178 is also typically driven via a belt by the diesel engine 175. The volumetric flow rate of centrifugal fan 178 is typically much greater than that of the compressor 176 in order to create the vacuum required.

As illustrated in FIG. 21, the centrifugal fan 178, which in the preferred embodiment is a squirrel cage fan, is provided to draw particulate detritus into the dust filtration unit 179 at the rear of the device. In the preferred embodiment, the dust filtration unit 179 is a cyclone provided with a dust collection bag.

The cleaning head of the embodiment illustrated in FIGS. 17 to 21 is also generally rectangular although smaller in footprint than the cleaning head of the “wet” embodiment. The plenum head of the dry embodiment is a fixed head (non-rotating) extending perpendicularly to the direction of travel of the vehicle. Compressed air outlets are spaced over the length of the plenum head and directed forwardly and downwardly at the surface.

As illustrated in FIGS. 19 and 20, the cleaning head 173 can be moved between a lowered working position and a raised transport position.

The device also includes a broom or brush 180 located at the rear of the vehicle in order to even distribution of any sand that is picked up by the vacuum but which falls back to the surface. A pneumatic ram or cylinder is provided to apply downward force at a preferred level of 50 kg to the broom or brush 180 The pneumatic ram is provided with air from the screw compressor 176.

This device also includes a retractable hose reel 181 mounting a hose for washing or cleaning.

In use, the compressor will provide compressed air to the plenum head through the compressed air supply conduit 183 which attached to the cleaning head 173 at the compressed air inlet 184. The compressed air exiting the outlets on the plenum head dislodge detritus which is then removed from the cleaning head 173 by the vacuum and carried through the vacuum conduit 182 to the duct filtration unit 179. The vacuum is not sufficiently strong to pick up the denser sand particles and/or an internal baffle structure is provided within the cleaning head, to separate the sand from the detritus on the basis of particle velocity.

In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations. 

1. An apparatus for cleaning synthetic grass comprising a manifold and an elongate plenum head disposed within the manifold and having a compressed air inlet and a plurality of air outlets spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of coarse and fine particulate material and to entrain the dislodged particulate material, said manifold including at least one vacuum outlet located in a rear area of the manifold associated with a vacuum system for exit of the fine particulate material, and an open lower region of the manifold for distributing the coarse particulate material back to the synthetic grass surface.
 2. An apparatus for cleaning synthetic grass comprising a manifold and an elongate plenum head disposed within the manifold and having a compressed air inlet and a plurality of air outlets spaced therealong through which air can be expelled against the synthetic grass surface for dislodgement of particulate detritus, said manifold including at least one vacuum head located rearwardly of the manifold associated with a vacuum system for exit of the particulate detritus, and an open lower region of the manifold, the manifold having at least one inlet therein to allow additional air or water to be provided into the manifold.
 3. An apparatus according to claim 1 adapted to clean synthetic grass with sand infill wherein the fine particulate material is detritus and the coarse particulate material is sand.
 4. An apparatus according to claim 2 adapted to clean synthetic grass with water infill wherein the compressed air entrains the particulate detritus in water for collection by the vacuum system.
 5. An apparatus accordingto claim 1 wherein the plenum head is mounted substantially horizontally in the manifold for rotation about a substantially vertical axis.
 6. An apparatus according to claim 1 wherein the plenum head is mounted substantially horizontally in the manifold for rotation about a substantially horizontal axis.
 7. An apparatus according to claim 1 wherein one or more ports are provided in the manifold for addition of air into the manifold.
 8. An apparatus according to claim 1 wherein one or more ports are provided in the manifold for addition of water into the manifold.
 9. An apparatus according to claim 1 wherein the plenum head includes a plurality of air outlets grouped at either end of the plenum head.
 10. An apparatus according to claim 1 wherein the plenum head includes a plurality of air outlets spaced substantially equally over the length of the plenum head.
 11. An apparatus according to claim 1 wherein the plenum head is adjustably mounted relative to the manifold in order to adjust the separation distance between the plenum head and the surface to be cleaned.
 12. An apparatus according to claim 1 wherein the at least one vacuum outlet is located in the manifold.
 13. An apparatus according to claim 1 wherein the at least one vacuum outlet is located behind the manifold in the direction of travel.
 14. An apparatus according to claim 1 further including a broom located behind the manifold in the direction of travel.
 15. An apparatus according to claim 1 wherein the device is a self-propelled vehicle with the manifold at a forward end, the manifold being movable between a lowered use condition and a raised condition in order to shorten the vehicle for maneuverability.
 16. An apparatus according to claim 1 wherein a water separation system is associated with the vacuum system to separate detritus from water, the water separation system including a filter bag through which the water is passed to separate detritus from water.
 17. An apparatus according to claim 16 wherein the filter bag is supported within a filter basket within a tank.
 18. An apparatus according to claim 1 wherein a cyclone particulate separation system is associated with the vacuum system to separate particulates of different sizes.
 19. An apparatus according to claim 1 wherein the manifold includes at least one inlet therein to allow additional air or water to be provided into the manifold. 